According to this depending on your setup you can handle this load.
http://www.fordf150.net/specs/05f150.php
I am taking mine out tomorrow and testing out the electric brakes. I did not have those bringing it home and it was ugly!
Actually displayed proudly on my hitch it says that with a WD hitch I can haul 9,900K with a ball hitch, and only 5,500K with out it!
What is funny is you can haul 5K right on the bumper no hitch required. Just install the ball to the hole in the bumper. I found that interesting. Dry, and marginally loaded I can bumper tow this trailer